<!DOCTYPE html>
<html>
<head>
    <title>表单示例</title>
</head>
<body>
    <form action="/submit_form" method="post"> <!-- action属性指定表单数据提交的URL，method指定提交方式 -->
        <label for="name">姓名:</label>
        <input type="text" id="name" name="name"><br><br>
        
        <label for="age">年龄:</label>
        <input type="number" id="age" name="age"><br><br>
        
        <label for="city">城市:</label>
        <select id="city" name="city">
            <option value="beijing">北京</option>
            <option value="shanghai">上海</option>
            <option value="guangzhou">广州</option>
        </select><br><br>
        
        <label for="message">留言:</label>
        <textarea id="message" name="message"></textarea><br><br>
        
        <input type="submit" value="提交">
    </form>
</body>
</html>